// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/gfx/nine_image_painter.h"

#include <stddef.h>

#include <limits>

#include "base/macros.h"
#include "third_party/skia/include/core/SkPaint.h"
#include "third_party/skia/include/core/SkRect.h"
#include "third_party/skia/include/core/SkScalar.h"
#include "ui/gfx/canvas.h"
#include "ui/gfx/geometry/insets.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/rect_conversions.h"
#include "ui/gfx/geometry/safe_integer_conversions.h"
#include "ui/gfx/image/image_skia_operations.h"
#include "ui/gfx/scoped_canvas.h"
#include "ui/gfx/skia_util.h"

namespace gfx {

namespace {

    int ImageRepWidthInPixels(const ImageSkiaRep& rep)
    {
        if (rep.is_null())
            return 0;
        return rep.pixel_width();
    }

    int ImageRepHeightInPixels(const ImageSkiaRep& rep)
    {
        if (rep.is_null())
            return 0;
        return rep.pixel_height();
    }

    void Fill(Canvas* c,
        const ImageSkiaRep& rep,
        int x,
        int y,
        int w,
        int h,
        const SkPaint& paint)
    {
        if (rep.is_null())
            return;
        c->DrawImageIntInPixel(rep, x, y, w, h, false, paint);
    }

} // namespace

NineImagePainter::NineImagePainter(const std::vector<ImageSkia>& images)
{
    DCHECK_EQ(arraysize(images_), images.size());
    for (size_t i = 0; i < arraysize(images_); ++i)
        images_[i] = images[i];
}

NineImagePainter::NineImagePainter(const ImageSkia& image,
    const Insets& insets)
{
    std::vector<gfx::Rect> regions;
    GetSubsetRegions(image, insets, &regions);
    DCHECK_EQ(9u, regions.size());

    for (size_t i = 0; i < 9; ++i)
        images_[i] = ImageSkiaOperations::ExtractSubset(image, regions[i]);
}

NineImagePainter::~NineImagePainter()
{
}

bool NineImagePainter::IsEmpty() const
{
    return images_[0].isNull();
}

Size NineImagePainter::GetMinimumSize() const
{
    return IsEmpty() ? Size() : Size(images_[0].width() + images_[1].width() + images_[2].width(), images_[0].height() + images_[3].height() + images_[6].height());
}

void NineImagePainter::Paint(Canvas* canvas, const Rect& bounds)
{
    // When no alpha value is specified, use default value of 100% opacity.
    Paint(canvas, bounds, std::numeric_limits<uint8_t>::max());
}

void NineImagePainter::Paint(Canvas* canvas,
    const Rect& bounds,
    const uint8_t alpha)
{
    if (IsEmpty())
        return;

    ScopedCanvas scoped_canvas(canvas);

    // Painting and doing layout at physical device pixels to avoid cracks or
    // overlap.
    const float scale = canvas->UndoDeviceScaleFactor();

    // Since the drawing from the following Fill() calls assumes the mapped origin
    // is at (0,0), we need to translate the canvas to the mapped origin.
    const int left_in_pixels = ToRoundedInt(bounds.x() * scale);
    const int top_in_pixels = ToRoundedInt(bounds.y() * scale);
    const int right_in_pixels = ToRoundedInt(bounds.right() * scale);
    const int bottom_in_pixels = ToRoundedInt(bounds.bottom() * scale);

    const int width_in_pixels = right_in_pixels - left_in_pixels;
    const int height_in_pixels = bottom_in_pixels - top_in_pixels;

    // Since the drawing from the following Fill() calls assumes the mapped origin
    // is at (0,0), we need to translate the canvas to the mapped origin.
    canvas->Translate(gfx::Vector2d(left_in_pixels, top_in_pixels));

    ImageSkiaRep image_reps[9];
    static_assert(arraysize(image_reps) == arraysize(images_), "");
    for (size_t i = 0; i < arraysize(image_reps); ++i) {
        image_reps[i] = images_[i].GetRepresentation(scale);
        DCHECK(image_reps[i].is_null() || image_reps[i].scale() == scale);
    }

    // In case the corners and edges don't all have the same width/height, we draw
    // the center first, and extend it out in all directions to the edges of the
    // images with the smallest widths/heights.  This way there will be no
    // unpainted areas, though some corners or edges might overlap the center.
    int i0w = ImageRepWidthInPixels(image_reps[0]);
    int i2w = ImageRepWidthInPixels(image_reps[2]);
    int i3w = ImageRepWidthInPixels(image_reps[3]);
    int i5w = ImageRepWidthInPixels(image_reps[5]);
    int i6w = ImageRepWidthInPixels(image_reps[6]);
    int i8w = ImageRepWidthInPixels(image_reps[8]);

    int i0h = ImageRepHeightInPixels(image_reps[0]);
    int i1h = ImageRepHeightInPixels(image_reps[1]);
    int i2h = ImageRepHeightInPixels(image_reps[2]);
    int i6h = ImageRepHeightInPixels(image_reps[6]);
    int i7h = ImageRepHeightInPixels(image_reps[7]);
    int i8h = ImageRepHeightInPixels(image_reps[8]);

    i0w = std::min(i0w, width_in_pixels);
    i2w = std::min(i2w, width_in_pixels - i0w);
    i3w = std::min(i3w, width_in_pixels);
    i5w = std::min(i5w, width_in_pixels - i3w);
    i6w = std::min(i6w, width_in_pixels);
    i8w = std::min(i8w, width_in_pixels - i6w);

    i0h = std::min(i0h, height_in_pixels);
    i1h = std::min(i1h, height_in_pixels);
    i2h = std::min(i2h, height_in_pixels);
    i6h = std::min(i6h, height_in_pixels - i0h);
    i7h = std::min(i7h, height_in_pixels - i1h);
    i8h = std::min(i8h, height_in_pixels - i2h);

    int i4x = std::min(std::min(i0w, i3w), i6w);
    int i4y = std::min(std::min(i0h, i1h), i2h);
    int i4w = std::max(width_in_pixels - i4x - std::min(std::min(i2w, i5w), i8w), 0);
    int i4h = std::max(height_in_pixels - i4y - std::min(std::min(i6h, i7h), i8h), 0);

    SkPaint paint;
    paint.setAlpha(alpha);

    Fill(canvas, image_reps[4], i4x, i4y, i4w, i4h, paint);
    Fill(canvas, image_reps[0], 0, 0, i0w, i0h, paint);
    Fill(canvas, image_reps[1], i0w, 0, width_in_pixels - i0w - i2w, i1h, paint);
    Fill(canvas, image_reps[2], width_in_pixels - i2w, 0, i2w, i2h, paint);
    Fill(canvas, image_reps[3], 0, i0h, i3w, height_in_pixels - i0h - i6h, paint);
    Fill(canvas, image_reps[5], width_in_pixels - i5w, i2h, i5w,
        height_in_pixels - i2h - i8h, paint);
    Fill(canvas, image_reps[6], 0, height_in_pixels - i6h, i6w, i6h, paint);
    Fill(canvas, image_reps[7], i6w, height_in_pixels - i7h,
        width_in_pixels - i6w - i8w, i7h, paint);
    Fill(canvas, image_reps[8], width_in_pixels - i8w, height_in_pixels - i8h,
        i8w, i8h, paint);
}

// static
void NineImagePainter::GetSubsetRegions(const ImageSkia& image,
    const Insets& insets,
    std::vector<Rect>* regions)
{
    DCHECK_GE(image.width(), insets.width());
    DCHECK_GE(image.height(), insets.height());

    std::vector<Rect> result(9);

    const int x[] = {
        0, insets.left(), image.width() - insets.right(), image.width()
    };
    const int y[] = {
        0, insets.top(), image.height() - insets.bottom(), image.height()
    };

    for (size_t j = 0; j < 3; ++j) {
        for (size_t i = 0; i < 3; ++i) {
            result[i + j * 3] = Rect(x[i], y[j], x[i + 1] - x[i], y[j + 1] - y[j]);
        }
    }
    result.swap(*regions);
}

} // namespace gfx
